The invention relates to a method of and to an apparatus for making a composite stream from fibrous material of the tobacco processing industry. More particularly, the invention relates to improvements in a method of and in an apparatus for making a stream of fibrous material wherein batches consisting of or containing fibrous material of a first type alternate with batches or accumulations consisting of or containing fibrous material of a second type. Still more particularly, the invention relates to improvements in a method of and in an apparatus for making a stream of comminuted natural, substitute and/or reconstituted tobacco wherein portions consisting of high-quality tobacco alternate with portions consisting of lower-quality tobacco or tobacco having other characteristics which deviate from those of high-quality tobacco.
The term "fibers" is intended to embrace all kinds of fibrous materials which are used in the tobacco processing industry, such as natural, reconstituted or artificial tobacco or substitute tobacco (for example, cellulose) as well as fibers which can be utilized to make filters for tobacco smoke. If the fibrous material is tobacco, it can consist of arromatic tobacco particles with a high or low nicotine content or of relatively mild tobacco which may have a high or low nicotine content.
Commonly owned U.S. Pat. No. 4,009,722 to Wahle et al. and commonly owned patent application Ser. No. 575,169 (filed Jan. 30, 1984 by Goldbach) disclose apparatus for accumulating tobacco shreds into batches which are thereupon converted into portions of a continuous tobacco stream wherein the batches alternate with accumulations consisting of a different type of tobacco. The batches are formed in the pockets of a rotary wheel and are transferred onto a belt conveyor in such a way that neighboring batches of the resulting single file of batches are separated from each other by gaps of predetermined length. The file of batches is transported past a duct which showers tobacco particles not only onto the batches but also into the gaps between neighboring batches so that the fibrous material which accumulates in the gaps constitutes a second file of batches consisting of a different type of fibrous material The resulting stream has an undulate outline and, therefore, it must be trimmed by removing the surplus prior to draping it into a web of cigarette paper or the like so as to form a continuous rod which is thereupon subdivided into plain cigarettes of unit length or multiple unit length.
A drawback of presently known apparatus for making a composite stream wherein batches containing a first type of fibrous material alternate with batches or accumulations containing a second type of fibrous material is that the quantity of surplus fibrous material in the stream is very high so that a large mass of removed fragments of tobacco leaves or other fibrous material must be recovered and recirculated for renewed use. This affects the economy of the operation and the quality of the recirculated fibrous material.